Copying processes



United States Patent 3,034,428 COPYING PROCESSES Frederick Ellam,Mattingley, Hants, England, assignor to Ellams Duplicator CompanyLimited, Watford, Herts, England Filed Aug. 26, 1957, Ser. No. 680,355 3Claims. (Cl. 101-1495) This invention relates to methods and means forproducing copies of matter to be copied, in which methods severalhundreds of copies are made on copy sheets from a single master carriersheet without recourse to more than slight local pressure, as distinctfrom methods for producing small numbers of copies on copy sheetswithout the use of a master carrier sheet, e.g. six or eight copies,with the aid of high local pressure, as for instance by means ofa'typewriter or a stylus. A well known method for producing copies is toprepare a mirror image of the matter to be copied by the use of a papercoated with a mixture of a soluble dyestuif, oils and waxes, the mirrorimage of the matter being formed by transferring the required portionsof the coating from the coated paper on to another sheet of paper bysuperimposing the sheets and acting on the coated sheet by means of atypewriter, a printing machine, a stylus, or other means.

i The sheet carrying the mirror image is then brought into contact underpressure with sheets of paper which have been moistened with a solventfor the dyestufi. The method usually employed for moistening thesesheets of paper consists in passing the sheets over a roller or a feltpad damped with a suitable solvent, such as industrial methylatedspirits, immediately prior to their being brought into contact with themirror image. This method suffers from the disadvantages that a uniformdegree of damping is difficult to obtain, and that highly volatilesolvents are usually required, which have undeniable inflammableproperties.

An alternative method has been proposed whereby the paper is moistenedbeforehand with a mixture of water and glycerine, but this methodsuffers from the disadvantage that the sensitivity of the paper varieswith the moisture content of the atmosphere.

It is therefore an object of the invention to provide a method ofproducing copies which eliminates variations in the copies due toirregularity in the degree of dampness of the sheets of paper causedeither by variations in atmospheric humidity or by lack of uniformity ofdamping.

According to one aspect of the invention, a method of producing copiesof matter to be copied comprises forming a mirror image of the matter,in a composition containing a soluble dye, on a carrier, and producingreversed impressions on copy sheets by bringing into contact with themirror image on the carrier a succession of said copy sheets, each copysheet having a solid surface coating containing a solvent for the dye,and wherein the method is carried out in the absence of moisture otherthan that present in the ambient atmosphere.

According to another aspect, the invention comprises a copy sheet foruse in a method of copying in which reversed impressions of a mirrorimage of matter to be copied, formed in a soluble dye on the surface ofa carrier, are produced on copy sheets, comprising a sheet of paperhaving a solid anhydrous coating on at least one side, said coatingincluding a non-volatile solvent for the dye, and a binder for thesolvent.

In addition, the coating may contain a white pigment to'reduce thetransparency of the paper and the solvent may be a long chain fattyalcohol. A precipitant for the dyestuflf may also be incorporated in thecoating on the copy sheets.

3,034,428 Patented May 15, 1962 According to a further aspect, theinvention includes a method of producing copies wherein the image of thematter to be copied which is formed on the carrier is a right image, andthe reversed impressions produced on the copy sheet are mirror images,each copy sheet being sufiiciently translucent to permit the mirrorimagev impression produced on the coated side thereof to be legible as aright image from the other side thereof.

According to yet another aspect, the invention includes a copy sheet foruse in a method of copying in which reversed impressions of a rightimage of matter to be copied, formed in a soluble dye on the surface ofa carrier, are produced on copy sheets, comprising a sheet oftranslucent base paper having a solid anhydrous coating on one side onlysaid coating including a white pigment, a non-volatile solvent for thedye, and a binder for the solvent.

Embodiments of the invention will be described with reference to theaccompanying drawings, in which:

FIGURES l to 4. represent, in diagrammatic form, four steps in onemethod according to the invention, and

FIGURES 5 to 8 represent, in diagrammatic form,'

four corresponding steps in another method according to the invention.

Referring to the method illustrated in FIGURES 1 to 4, the copy paper iscoated on a separate machine with a composition consisting of oleylalcohol as a non-volatile solvent for the dyestufi, a binder consistingof nitrocellulose, and a white pigment consisting of titanium dioxide.The composition is prepared by dissolving the oleyl alcohol andnitrocellulose in a mixture of alcohol and ether and stirring in thetitanium dioxide. The composition is then applied on a conventionalpaper coating machine.

The binder prevents excessive penetration of the solventinto the paperand the titanium dioxide reduces the transparency of the coated paper.

The invention will be illustrated by the following examples in which allparts are expressed as parts by weight.

Example 1 parts of titanium dioxide are ground into 258 parts of oleylalcohol and added gradually to a solution of 60 parts of a mixture of 70parts of industrial nitrocellulose {H.L. /170) (I.C.I. Ltd.) and 30parts of industrial methylated spirits, in 360 parts of n-butyl acetate,the mixture being stirred during the addition.

The resulting liquor is then applied to one surface of a white paper,which has a weight of 28 gm./sq. m., by known coating procedure and thepaper is heated to drive off the n-butyl acetate and methylated spirit.The thickness of the coating is such that after evaporation of the abovesolvents a uniform coating Weighing about 5 gm./ sq. m. is obtained. Thecoated paper is then cut up into sheets which will be referred to ascopy sheets.

A mixture of 60 parts of Methyl Violet l0 B.N.S. (Imperial ChemicalIndustries Ltd), 10 parts of carnauba wax and 30 parts of petroleumjelly is ground until a fine dispersion of the dye in the oil and waxmixture is obtained. The mixture is then melted and coated by knowncoating procedure on to a paper weighing 50 gm./sq. in. so that auniform coating weighing 20 gm./ sq. m. is obtained. This coated paperis subsequently referred to as the carbon paper.

A sheet of the carbon paper, indicated at 10 in FIG- URE 1, is placedcoated side upwards on a flat metal base 11 and a piece of white, smoothsurfaced paper 12 weighing 85 gm./sq. m. is placed over the carbon paper10. This sheet of white paper 12 will subsequently be referred to as thecarrier. The carrier 12 is then written on with a stylus 13 usingsufiicient local pressure to transfer the coating a from the carbonpaper 10 to the carrier'12 and thereby obtain a dense mirror image 10bof the matter to be copied on the back of the carrier 12. This isclearly shown in FIGURE 2.

' The carrier 12 is then placed on a smooth, hard, fiat surface 14 withthe mirror image 101; face upwards and a copy sheet 15 is placed overthe carrier 12 with its coated surface 15a-downward's. A rubber squeegee(not shown) is then drawn over the uppermost Surface of the copy sheet'15 so that it is pressed into intimate contact with the carrier 12. Afaint image 15b of the matter to be copied appears on the copy sheet 15and increases in strength until a bright purple copy results. Theprocess may be repeated with fresh copy sheets until about 50 copieshave been obtained.

Instead of using oleyl alcohol for the solvent, decyl alcohol, n-hexylalcohol or benzyl alcohol may be used. Example 2 The copying process isimproved if a precipitant for the dyestulf is added to the coating onthe copy sheets. The addition of a precipitant prevents the tendency forv the matter on the copies to spread during storage.

A suitable precipitant must be soluble in the coating compositionapplied to the copy sheets and must be capable of re-acting with thedyestufi transferred to the copy paper to produce a coloured productwhich is insoluble in the coating of the copy paper. It is probable thata very rapid reaction between the precipitant and the dyestuff' isundesirable as this would prevent the copies developing to asatisfactory strength during the first few minutes after copying. it hasbeen found that a suitable precipitant, when using the carbon paper described in Example 1, is phosphomolybdic acid.

A- composition for coating the copy paper may be made up as in Example 1except that before the liquor is applied to the paper a solution of 3.85parts of phosphomolybdic acid in 385 pants of industrial methylatedspirit (740 o.-p.), is added.

After coating, the paper is heated to drive off the solvents and thenused asin Example 1'.

I have found that the benefits'of the invention may be extended to amodification of the method in which is right image is produced on thecarrier instead of the mirror image, as produced in the aforesaidmethod.

Example 3 A liquor is made up in accordance with Example 1 and isapplied by known coating procedure to a base paper'as described in thatexample. The base paper, however, instead of being the white paperpreviously specified, is a translucent paper known as ImitationParchment having a weight of 45 g n/sq. m.

, sure to transfer the coating 10a from the carbon paper 10 to thecarrier and thereby obtain a dense true or right image 100 of the matterto be copied on the top side of the carrier 20, as shown in FIGURE 6.

The copies are produced as follows: After discarding the carbon'paper 10a copy sheet 21 is placed over the carrier 29, coated side 21adownwards, as shown in FIG- URE 7. A squeegee (not shown) is then drawnover the uppermost surface ofthe copy paper. 21 so that it is pressedinto intimate contact with the carrier 20. A faint mirror image 21b ofthe matter to be copiedappears on the coated side 21a of the copy sheet21 and increases in strength until a bright purple copy results. On theuncoated side of the copy paper 21 a true image is visible through thetranslucent base paper, as shown in FIGURE 8. The process may berepeated with fresh copy sheets until about 50 copies have beenobtained.

The presence of the pigment in the copy paper 21 is important as itconceals the translucent nature of the paper during normal use, but theimage 21b is enabled to be read through the paper 21 after the copy hasbeen made.

Instead of using carbon paper the carrier may be prepared by typing onto it using a typewriter ribbon which is impregnated with a mixture ofsoluble dyestufis such as Methyl Violet 10 B.N.S. and mineral oil.

I claim:

1. A dry method for producing copies of matterto be.

copied, which method comprises the steps of forming an image of thematter in a composition containing a nonvolatile soluble dye, on acarrier sheet, thereafter producing impressions on copy sheets bybringing into contact with the image on the carrier sheet a successionof said copy sheets without previous moistening, each copy sheet havinga solid surface coating containing a nonvolatile solvent for the dye,said solvent being selected from the group consisting of oleyl, decyl,'nhexyl and benzyl alcohols, and a nitrocellulose binder for saidnonvolatile solvent, whereby an impression is produced on said coatingwithout said sheets having to be moistened prior to use.

' 2. A dry method for producing copies of matter to be copied, whichmethod comprises the steps of forming an image of the matter, in acomposition containing a nonvolatile soluble dye, on a carrier sheet,thereafter producing impressionson copy sheets by bringing into contactwith the image on the carrier sheet a succession of said copy sheetswithout previous moistening, each copy sheet having a solid surfacecoating containing a longchain fatty alcohol non-volatile solvent,-and anitrocellulose binder for said non-volatile solvent, whereby animpression is produced on said coating without said sheets having to bemoistened prior to use.. 7 l

3. The product produced in accordance with the process of claim 2.

References Cited in the file r this patent UNITED STATES PATENTS 652,287Paltridge June 26, 1900 901,824 Brias et al Oct. 20, 1908 1,923,625Jackson Aug. 22, 1933 2,163,934 Collins June 27, 1939 2,271,758 ChampionFeb. 3, 1942 2,288,389 Bout June 30, 1942 2,337,737 Champion Dec. 28,1943 2,348,128 Groak May 1, 1944

